Bearing preload

Preload is a force acting between the rolling elements and bearing rings that is not caused by an external load. Preload can be regarded as negative internal clearance. Reasons to apply preload include:

enhanced stiffness

reduced noise level

improved shaft guidance

extended bearing service life

improved running accuracy

prevent skidding in high-speed applications during rapid starts and stops and under very light or no-load conditions

In the majority of high-precision applications preload is needed to enhance system rigidity.